They're both great oils, the numbers come down to price and availability. I've never seen Shell HM at a parts store or on sale. I'd definitely buy it on a special, but the days of Rite Aid putting motor oil on sale--much less having great deals--are long gone. They used to be great for picking up Havoline here as they often had it for about a $1 a qt. on sale, but long since stopped carrying it...

Shell may make MotoMaster's Formula 1 High Mileage Oil, but they also make Pennzoil's High Mileage Oil and Quaker State's Defy High Mileage Oil, all with different specs... Canadian Tire's Shell MSDS shows practically nothing. I tried inquiring with Shell over a week ago.

An MSDS isn't supposed to show much of anything. Most of the technical data sheets that Shell has these days are questionable anyhow. I'm sure Shell will tell you to ask Canadian Tire, since it's their branded oil, and Canadian Tire will tell you to ask Shell, since they make the product.